1. Field of the Invention
The invention relates to the field of material-recovery operations. More particularly, the invention relates to the recovery of valuable, usable material from under-utilized and waste-stream material. More particularly yet, the invention relates to the use of material-removing tools in the recovery of usable material from under-utilized and waste-stream material of various shapes and sizes.
2. Description of the Prior Art
Inherent in a manufacturing process is that one or more products are produced according to specifications that define the shape and size of the product, that is, that each exemplar of the product produced by a particular process ideally has a shape and size according to the applicable specification. A particular problem in a manufacturing process in which an exemplar of a product is cut or otherwise produced by a material-removing process is that the material that is left over may have a shape or size that renders it useless for obtaining any more exemplars of the particular product according to specification, though it may contain sufficient material to provide one or more different products. In spite of such collateral use, such left-over material is normally deemed to be scrap and channeled into a waste-material stream in which the material is converted into a low-value chip or mulch by-product, discarded as waste into a landfill, or perhaps burned for fuel.
A sawmill is a typical example of a manufacturing operation that generates left-over material that may be useful material for other operations. The mill takes round logs, often with the bark still attached, and converts them into square and rectangular products. In the sawing process, material forming the outside perimeter of each log ends up as irregularly shaped slabs, edgings, and waney material of random thickness and/or width. The term xe2x80x9cwaneyxe2x80x9d as used hereinafter refers to stock or material that has waning, i.e., diminishing, dimensions, such as presented by a tapered piece of wood. Such waney material, however, often contains enough wood from which to obtain one or more pieces of a high-value product, such as uniformly dimensioned stock or blanks for turning or component stock. Although this material is potentially valuable, the sawmill owner is not interested in working with it, as the sawmill is not equipped for processing small pieces of short and/or irregularly shaped wood.
Wood is used in this discussion to illustrate the generation of material that is xe2x80x9cscrapxe2x80x9d for one particular type of manufacturing operation and a high-value material for another operation. It should be understood, however, that any material-removing process used to create a product will also produce a xe2x80x9cscrapxe2x80x9d material that may be remaindered, i.e., declared a left-over, material that is valuable and usable for manufacturing other high-value products. Hereinafter, xe2x80x9cscrapxe2x80x9d material that is usable to create other products will be referred to as xe2x80x9cremaindered materialxe2x80x9d. It should also be understood that, although wood is the material most commonly referenced herein as xe2x80x9cthe materialxe2x80x9d, other substances exist that can be used in a material-removing process to form articles or products. These include plastic materials, hard rubber, etc., are therefore also included in the definition of remaindered material in the following discussion of material-recovery operations.
Until now, it has been quite costly to process remaindered material because of the fact that the traditional approach requires several types of machines and several labor-intensive operations to process irregularly shaped pieces of material coming in a range of thicknesses, widths, and lengths, so as to render it useful. As a result, such remaindered material often flows into a waste-material stream or is chipped and burned as fuel. This is not only wasteful in terms of responsible use of natural resources, but cost-ineffective for several reasons.
The wood that is left over after the sawing or other material-removing processes is generally very expensive wood when valued on a cost-per-unit-weight or cost-per-unit-volume basis. Not only is the wood contained in this remaindered material generally jacket wood, i.e., the outer layer of wood on a tree, and the highest quality wood in the tree, it has also passed through one or more processing operations and has been handled extensively. It is economically wasteful not to extract as much value as possible from it. It is an irony that the very wood that is most desirable for manufactured wood products is being discarded as scrap for lack of a cost-effective, efficient way of extracting valuable, usable material from it.
Some manufacturers try to obtain at least some value for the wood left over from the material-removing processes by selling it as fuel, mulch, and/or paper chips. Using remaindered material as fuel has the disadvantage that the material has to be transported to the site where it is chipped and/or burned, thereby further reducing its already nominal value as fuel. Furthermore, there is a limit to the demand for products made from chipped wood fiber. For those reasons and the fact that there is an ever-increasing production of wood chips, chips are becoming less and less valuable as a by-product of wood-processing operations.
Manufacturers have for years attempted to solve the problems inherent in the utilization of remaindered wood, only to discover that it is simply not economically feasible to process material that comes in a range of widths, thicknesses, lengths, or irregular shapes. Such material requires multiple handling and processing steps to convert it into a more workable uniform and valuable product. The only known apparatus on the market for easily and economically converting scrap wood to usable dimensioned stock is a machine designed and constructed by the inventor of the present invention and that has been available for several years. This machine, the YIELD PRO Recovery machine, converts slabs, sawmill and ripsaw edgings, waney stock, and other mis-sized or random-shaped materials into uniform square-edged stock. The YIELD PRO Recovery machine is a large and rugged machine that has separate tool spindles and motors for the horizontal cutting tool and the vertical cutting tool, respectively, a lifting jack with several linear guides on each side of it, as well as a third motor for driving conveyors. This machine is capable of processing slab wood of sizes up to 4xe2x80x3 by 12xe2x80x3, can remove up to one inch of material from the top, and can even process material that has nails embedded in it. Because of its ruggedness, however, and its ability to handle large pieces of wood, this high-volume machine is relatively costly to manufacture and, thus, to acquire. Furthermore, because of its relatively large footprint, requires a lot of floor space.
Primary operations in the wood-products industry include such operations as sawing boards from logs in sawmills; secondary operations include such operations as turning round stock and cutting relatively small component pieces. Although primary operations are the largest source of remaindered material suitable for recovery processes, secondary operations such as furniture-making also provide significant amounts of remaindered material suitable for recovery. Currently, the remaindered material from secondary operations, as well as from primary operations, is treated as waste material and is funneled into the waste stream to be chipped and/or burned.
The remaindered material from secondary operations is generally even more valuable then that from primary operations. For example, in furniture-making operations, the material is likely to be kiln-dried wood that has been through any number of shaping and forming operations. The particular difficulty with recovering usable material from the remaindered material from secondary operations is that the dimensions of this material are typically much smaller than the remaindered material generated by primary operations. On the other hand, a machine that is as rugged as the YIELD PRO Recovery machine described above is not necessary to process the remaindered material generated by secondary operations. For example, wood from furniture-making operations will not have nails embedded in it; also, such wood will not be covered with bark and, therefore, less material will need to be removed from the top. Furthermore, remaindered material from secondary operations will also generally be shorter in length than much of the remaindered material from a sawmill.
For these reasons, a machine that is less expensive to manufacture and that is small enough that it can be moved around to different work stations in a plant, and that requires less energy to operate, will be more desirable to potential buyers and, therefore, pose a lower threshold for manufacturers to overcome if they are otherwise enticed by economics and/or environmental or other concerns to recover more material for higher value-uses than the burning of it for fuel.
One aspect that is critical to proper operation of the material-recovery apparatus is its feed system. When material is fed into a machine to be cut by material-removing tools, the tendency is for the material to be kicked back from the rotating cutters that resist the advance of the material. For this reason, the feed conveyor is provided with a surface that prevents material from slipping in the direction opposite to the feed direction, and feed rollers are mounted on the machinery to keep the material pressed against the conveyor. The feed rollers on the conventional machinery are attached to bearing-mounted tensioning units that apply a downward biasing force to the feed rollers. When the material feeds into the machine, these feed rollers are forced upward against the biasing force by the in-feeding material. The apparatus is designed so that the rollers accommodate the material, yet maintain sufficient downward force on it to ensure that it is carried into the cutting tools. Conventional tensioning units use a bearing-mounted spindle, around which a tensioning spring is coiled. A disk having a plurality of evenly-spaced holes around its outer perimeter is mounted at one end of the tensioning spindle. By turning the disk and inserting a locking pin into one of the holes, one moves the disk so as to bias it to apply a torque in one direction, while it remains free to rotate in the opposite direction if a force strong enough to overcome the biasing torque is applied to it. The disadvantage of the conventional tensioning unit is that, because of the machining and the amount of material necessary to provide a secure mount, it is quite expensive to manufacture.
What is needed, therefore, is material-recovery apparatus that is easy to operate, readily portable, and relatively inexpensive to manufacture. What is further needed is such apparatus that will accept material of various widths, thicknesses, lengths, and irregular shapes, and produce a square-edged product with a single pass of the material through the apparatus. What is yet further needed is such apparatus that is easily adjustable so as to produce square-edge stock in a range of sizes and relative dimensions. And, finally, what is needed is such apparatus that requires less power to operate and less maintenance.
For the above-cited reasons, it is an object of the present invention to provide material-recovery apparatus that is mechanically uncomplicated, easily portable, economical to manufacture, and that requires a minimum time for set-up and maintenance. It is a further object to provide such apparatus that can accept material of various dimensions and irregular shapes and produce a square-edged product with a single pass of the material through the apparatus. It is a yet further object to provide such apparatus that is easily adjustable and can produce square-edged product in a range of varying dimensions.
The objects are achieved by providing material-recovery apparatus that is small in size and light enough to be easily portable, is made up of mechanically simple components, is energy-efficient and versatile, requires little effort to set up, operate, and maintain, and that produces uniform dimensioned stock from remaindered material of irregular dimensions and shapes. The apparatus according to the invention has a single tool spindle driven by a single motor. The single spindle supports two cutting tools that perform two different machining tasks simultaneouslyxe2x80x94the planing of the top face and the sawing of the outside edge of the material being processed. As the remaindered material is fed into the apparatus, feed rollers placed before and after the tool spindle bear down on the material and press it against a feed conveyor that forces it through the cutting operation.
The referenced feed rollers are forced down against the material on the conveyor by tensioner units that are designed so as to allow the rollers to adapt to varying thicknesses of an in-feeding workpiece while yet reliably holding the workpiece against the feed conveyor for feed and cutting operations. These tensioner units are the heart of the invention and are quite different from their counterparts in the Yield Pro prior art. Each tensioner unit is constructed of simple components that make it less expensive to construct than the known bearing-mounted tensioner units. Furthermore, the new tensioner unit according to the invention is easy to maintain and is effective in applying a downward pressure onto the workpiece feeding into the cutting operation, even if the workpiece varies in thickness and shape, or each workpiece varies from the others being processed.
Remaindered material such as that produced in a sawmill or in a plant that produces moldings or blanks for round stockxe2x80x94for example, broom handles or dowelsxe2x80x94includes pieces of slab wood, waney stock that has a diminishing dimension such as thickness or width or both, edgings, irregularly shaped pieces such as molding, and wood that has an unacceptable or unworkable section. Generally, such remaindered material has two flat faces that intersect perpendicularly to one another. It is this type of material that can be processed into usable stock with a single pass through the apparatus according to the present invention. Remaindered material that has only one flat surface requires two passes through the apparatus to produce four-sided square-edged stock.
One of the key features of the new recovery apparatus is its simplicity. As mentioned above, it requires but a single-spindle machine driven by a single motor. Horizontal and vertical cutting tools are mounted on this single tool spindle to provide simultaneously two right-edged cuts along the top and the left vertical surface, respectively, of the workpiece fed through the apparatus. The housing that supports the feed rollers and the tool spindle of the new apparatus is shorter than that of the prior art and is supported, guided, and horizontally balanced by a single lifting jack, without linear guides.